Kiln and method of firing the same



, Dec. 20, 1949 E. E. sLlcK KILN AND METHOD OF FIRING THE SAME 3Sheets-Sheet l Filed Deo. 14, 1946 Irllllll l nventor Edwin .SlickGttomeg 5* Dec. 20, 1949 E E, SUCK 2,491,625

KILN AND METHOD oF FIRING THE SAME Filed Dec. 14, 194e 3 Sheets-5heet 2M' J5 I nventor Gttornegs Dec. 20, 1949 E. E. sLlcK KILN AND METHOD OFFIRING THE SAME 5 Sheets-Sheet 3 Filed Deo. 14, 1946 '1, Inn,

l l l Cttorneg 5I Patented Dec. 20, 1949 UNITED STATESEPATENT oFFiceKILN AND METHOD OF FIRING THE SAME Edwin E. siick',"rittsburgh, Pa..

Application December 14, 1946, Serial No. 716,366

7 Claims.. (Cl. 25-151) part of the kiln and the labor and skillrequired it has been proposed to use mechanical stokers of conventionaltype in which the coal is forced up through a central passage or retortand as it burns, the ash is clinkered and the clinkers removed from timeto time.

Many types of ceramic or refractory articles are extremely sensitive totemperature changes during burning. Silica brick, for example, is red ata temperature of around 2700 F. and the temperature must be graduallyand uniformly increased to avoid damage.

With hand firing of coal burners the attendant is very likely to let thefires burn down, then throw in a quantity of fuel, resulting in unevenfiring and the opening of the doors for throwing in coal and removingash admits cold air that is detrimental. Not infrequently as much as 10%of the w-are in the kiln is damaged by uneven firing, and a highpercentage of loss is always expected.

While conventional stokers tend to keep a more uniform rate ofcombustion the ash is accumulated in the fire pot and is converted intoa clinker. The operator must frequently open the fire door and removethese `clinkers. During this operation, air enters through the firedoor, tending to reduce thetemperature, thus detrimentally affecting theburning of the ware.

According to the present invention there is pro-` vided a stokerarrangement wherein the ash is continuously forced from the fire pot orcombustion zone as it is produced, where it falls into a pit in which itmay accumulate during the entire period of the operation of the firingof the kiln, or at least during that period of the firing which iscritical, so that it is unnecessary to open the firing door at any timeafter the fires have been Thereby it becomes possible to uniformlyincrease the temperature within the kiln and avoid damage to the ware..due to any sudden variation or dropping of the" temperature in anyparticular 'of the attendant is greatly reduced.

In the arrangement contemplated by the present invention the kiln isprovided with a number of similar stokers more or less equally spacedaround the side of the kiln. The coal feeds uniformly and continuouslyinto each Stroker moving radially toward the center of the furnace, andas it moves combustion takes place. At the inner end of the stoker unitthe coal will have been converted to ash and the ash drops out of thestoker into the ash pit where it may accumulate for a considerableperiod of time.

While the stoker has been especially designed for use in a brick burningkiln, it is also applicable to other operations where it is desired toautoz matically stoke and effect removal of the ashes of such furnace;

, 50` started, nor is it necessary to open the ash door.

, Fig. 2 is a side elevation of a portion of the furnace shown in Fig.`1;

Fig. 3 is a fragmentary section through the wall of the kiln showing oneof the stokers partly in side elevation and partly in section, the viewbeing on a larger scale than Figs. 1 and 2;

Fig. 4 is a horizontal section in the plane of line IV-IV of Fig. 3;

Fig. 5 shows the apparatus disclosed in Fig. 3 in an end elevation; and

Fig. 6 is a fragmentary transverse section through the fire-pot, theview being substantially in the plane of line VI--VI of Fig. 3.

Referring to the drawings there is shown a more or less conventionalform of kiln, which kiln is completely circular as is well understood bythose skilled in the art, and has a side wall 2 and a dome-shaped to-p3. One or more entrance doors are provided in the side at 4. The Stokerunits are designated generally as 5 and they are disposed at regularintervals around the periphery of the kiln with their longitudinal axesradial to the kiln.

As more clearly shown in Figs. 3, 4, 5 and 6, the stokers are providedwith a feed hopper 6 which delivers coal into a screw conveyor 1 thatextends horizontally beneath the hopper. A motor 8 drives a shaft 9,which in turn has a worm thereon for engaging a worm wheel l0 forturning alternas 3 the conveyor screw I I. The shaft 9 also drives ablower fan (not shown) but which is of conventional form, and which iscontained within a fan housing I2 alongside the gear box for the screwconveyor drive.

The fan housing has an intake opening I3 and delivers air into a duct I4that extends along one side of the screw conveyor tube 1 as most clearlyshown in Fig. 4. Both the screw conveyor and the duct pass through thewall 2 of the kiln.

The inner end of the screw conveyor tube opens into a trough-shapedretort or a nre-pot designated generally as I5 and which, as shown inFig. 5, extends radially inwardly. This retort or nre-box is shown inFig. 6 as having a rounded bottom I6 with upwardly diverging sides l1,these sides merging into outwardly-turned rim portions !8. A sheet metalcasing I9 extends downwardly from the edges of the rim I8 and under thebottom of the trough forming a wind box 20 into which the vair duct I4opens.

As best shown in Fig. v3, the top edge of the retort or nre-pot slopesdownwardly l.and inwardly while the linn'ern'rcst part `of the bottom ofthe ltrough I6 extends inwardly and upwardly, therebei'ig ja sornewhai'.rounded end wall portion EI at Athe inner `end of the trough. The sheetmetal casing I9 also joins the downwardlyturned flange ZI' at the outeredge of this rim for closing the wind box. The Yupwardly sloping portionof the bottom 1:6 is designated Iii (see Fig. s). l 4

The side rims :I8 yat each lside of the trough and the end rim vportion2-I are provided with numerous openings Ythat v direct currents of airinwardly and "upwardly toward the mid plane of the trough, thesevopenings providing the combustion air for lburning the fuel. The rim ofthe fire-pot thus constitutesa tuyr'e.

In 'operation the screw *delivers coal into the trough. The coal movesradially inwardly and upwardly filling the troughiand combustion takesplace lcontinuously 'along the rim which forms the tuyre for supplyingvthe Vcombustion air. There is progressive movement of -the whole bodyof coal inwardly and the rate of fee'd is so adjusted to the rate ofcon'ilcustion and the length of the trough that by the time lthe coalreaches the inner end ZI of the retort or combustion chamber it willhave been 'substantially entirely reduced to ash. This Vash fallsdownwardly in the space between the skirt 2l forming the end of thestoker lunit and the r,bag `wall 22 of the kiln. The stoker is supportedo'n bars 23 which are commonly vprovided `atrthe present time in kilns,and below the bars h2i! there is a large ash pit 24 or other ashreceiver which extends from the outer vertical wall inwardly toward thebag wall 22.

, l,As best seen in Fig. 5, there are two ash doors 26 opening into the'ash pit, V'one at each side of the mid plane ofthe, stoker which sealit against vfree inflow of outside air. `Likewise there are two nringdoors 21, fone being at each side of the fuel hopper and :affordingaccess to the combustion unit. All these doors are normally closedduring operation.

`As best shown in Figs. 4 'and 6, there is brick work 28 slo-pingupwardly and outwardly from the tops of the tuyres forprev'ent'ing [fuelfrom overflowing at the sides of Athe retort and allowing the burningfuel to spread yout toa limited extent.

VAll of the Stoker units are the same and while I have "shown oneparticular form lof drive for 4 the screw feeds of the stokers, it willbe understood that this is merely lby way of illustration, and thatvarious other drives for the screw feeds may be provided. Ordinarily inan operation of this kind the stoker operates more or less continuouslyand the rate of feed and the rate at which the fuel bed is moved iscoordinated to the length of the trough (and also the rate ofcombustion) to assure substantial consumption of the fuel before itreachesthe discharge end. This is simply obtained Yby a properadjustment of the feed of the screw or of the speed of the y motor whichdrives it. Each of the stokers provides an elevated trough-shaped retortor fire pot that iextends radially inwardly so that in the operation ofthe kiln there is at each station an inwardlyprogressing burning bed offuel which,

by the time it reaches the innermost end of the retort, has beensubstantially reduced to ash, and which before any substantialclinkering takesplace, discharges freely into the large ash pit "orashreceiver provided under the Stoker. This a'rrangeno'ent enablessubstantially uniform conditions of combustion to be maintained at eachnr'ing station and uniform rates of combustion to be maintained, and theoperation of firing can take place after the kiln is started withoutthere 'normally'being 4any need for opening the fire doors or the lashremoval doors. Hence ceramic articles, and particularly articles such assilica brick which are very sensitive during firing to any heat'changes,can be burned with-inet only Aa lc'msiderable economy of fuel, but Awithconsiderably less loss due to temper- Y alture changes. The ash"discharges beyond the Azone of combustion so that any dust that may beformed by the falling ash is in a quiescent atmosphere and is notcarried into the furnace. Y

-As hereinbefore indicated, wh'ile the Stoker has special'adaptation to'akiln ofthe class described, it is also applicable to otherarrangements where coal is to be burned and the `ash is to be auto-Iatoally discharged.

While -I have illustrated `and described one specic embodiment of myinvention, it will be understood that this is 'by way of illustrationand that various changes and finodications may be made therein.

1. A kiln for the burning of products to be red comprising a kilnstructure having side walls and "a roof, and a plurality of stokersaround the sidewalls of ythe kiln, each stoker beingconstructe'd tofnove a burning body of fuel at "a controlledra'te "inwardly toward thecenter o'f the kiln and ldischarge 'the ash at the end remote from ftheside wall.

2. A kiln for the burning of products to be fired comprising la/kilnstructure having side wallsan'd aroofjanda plurality of stokers aroundthe side walls'of the kiln, each stoker being coi.- structed to `move "aburning Ibody of fuel at a controlled rate `inwardly toward vthe centerof thekiln and discharge the ash at the end remote from th-e side wall,the kiln having an ash pit therein under the stoker for holding anaccumulation of ashes so discharged, said ash pit being closed againstfree circulation of air therethrough, each Stoker having means fordelivering air to the fuel bed under positive pressure. n 3. A kiln forthe burning of products to be nred comprising` 'a kiln structure havingside walls and a "roof, and stokermeans at a pluality Ioffst'atiori'saround `the wall of the kiln,

said stokers operating to move the fuel as it burns inwardly at acontrolled rate toward the center of the kiln and discharge theresulting ash at the inner end of the stoker, there being an ashcompartment under each stoker into which the ash is discharged and whichis normally closed against free ingress o-f outside air.

4. A kiln for burning ceramic and like articles comprising a circularstructure having a plurality of stokers around its periphery, eachstoker being provided with an inwardly elongated re pot whereby theburning coal moves progressively as it burns radially of the structureand discharges at the inner end thereof, each stoker having means foradvancing the burning fuel along the elongated ilre pot at a controlledrate, and means for supplying air to the lire-pot.

5. A kiln for burning ceramic and like articles comprising a circularstructure having a plurality of stokers around its periphery, eachstoker being provided with an inwardly elongated fire pot whereby theburning coal moves progressively as it burns radially of the structureand discharges at the inner end thereof, the nre-pot having an end wallto retard the free movement of fuel along the fire-pot and maintain thefuel bed at a controlled depth, the ash being discharged over the endwall, each stoker having means for effecting the movement of the fuelbed at a controlled rate along the hre-pot, and an ash receiver normallyclosed against ingress of outside air into which the ashes fall from theinner end of the stoker, the stoker having means for supplying air alongthe fire-pot to the fuel.

6. A kiln for burning ceramic and like articles comprising a circularstructure having a plurality of stokers around its periphery, an ash pitunder each stoker, each ash pit having an ash door for removal of ashestherefrom, each stoker being designed to progressively move coal as itburns at a controlled rate radially of the structure and discharge theash into the ash pit, there being a passageway at the inner end of eachstoker opening vertically into the iirepit, said passageway beinginwardly of the combustion zone and the ash pit being air-tight wherebya counter flow of air to float fine ash upwardly through the passagewayis avoided.

7. The method of ring a coal-red kiln which comprises progressivelyadvancing the coal while it is burning from several stations around theperiphery of the kiln toward the center at a controlled rate, droppingthe resulting ash at the end of its travel into an ash receiver which isnormally closed against the free inflow of out side air whereby firingtemperature in the kiln may be uniformly reached and opening of the kilnduring ring avoided.

EDWIN E. SLICK.

REFERENCES CITED The following references are of record iin the ile ofthis patent:

UNITED STATES PATENTS Number Name Date 316,397 Plumb Apr. 21, 18851,407,288 Marris i Feb. 21, 1922 1,599,103 Schlotterer Sept. 7, 19261,797,608 Goodwin Mar. 24, 1931 2,262,078 Yarick Nov. 11, 1941 2,362,127Gehl Nov. '7, 1944 FOREIGN PATENTS Number Country Date 453,304 GreatBritain Sept. 9, 19.36

